This invention relates generally to railyards, and more particularly to locomotive parking and servicing management within a railyard.
Most railyards must store incoming locomotives between assignments to trains, and many railyards also carry out service operations on locomotives. Both the parking and/or servicing of locomotives can affect the time at which they will be ready for service on an outbound train, so parking and service decisions can materially affect the overall performance of a railyard. In general, it is recognized that railyard management would benefit from the use management tools based on optimization principles. Such tools use a current railyard status and list of future tasks to be accomplished to determine an optimum order in which to accomplish these tasks such that railyard management objectives and rules are fulfilled.
As used herein, the term “locomotive consist” or “consist” means one or more locomotives physically connected together, with one locomotive designated as a lead locomotive and other locomotives designated as remote locomotives. The term “train consist” means one or more locomotives and one or more railcars physically connected together.
Railyards must store locomotives temporarily, when inbound or terminating trains are disassembled. The locomotives are parked in the yard, and placed back into service later as needed. Many yards include a locomotive service shop, and inbound locomotives therefore fall into one of four classifications: assigned to a later outbound train, needing no service, unassigned, and needing no service, assigned to a later outbound train, and needing service, and unassigned, and needing service. Depending on the locomotive's status and the schedule of inbound and outbound trains, a given locomotive may need to remain in the yard for a short while, or for a long time. The parking arrangement for locomotives should, if possible, accommodate the easy retrieval of locomotives at the time they must be moved, but limited parking facilities generally complicate the situation.
A typical parking arrangement for a railyard, comprises a collection of parallel tracks and a locomotive shop, located side-by-side. There is usually a direction of flow through the railyard with locomotives normally arriving at the parking complex, and later being pulled for service from the parking complex. However, an arriving locomotive will frequently be parked behind other locomotives, and if it is needed before one of those which precede it in the queue, then additional locomotives must be temporarily displaced in order to free the needed one. This represents an inefficiency, both in terms of time delay and labor hours needed to perform the extra activities.
Another inefficiency arises if locomotives slated for service are parked in a poor order. For example, a locomotive requiring 30 minutes of service, and slated for outbound use three hours later may be parked behind a locomotive requiring four hours of service. In order to meet schedule, the obstructing locomotive must be moved, again resulting in delay and cost in hostler hours.
There exists a need for a locomotive parking management scheme to ameliorate the inefficiencies which arise in any given parking/service configuration. As locomotives arrive, there will be several options available for parking them, either for use or for service. A desirable parking management scheme is one which is capable of weighing the cost of various parking options against the future locomotive requirements of the yard.